Veterans from two New Zealand frigates that were sent to protest French atmospheric nuclear testing at Mururoa Atoll in the Pacific in 1973, are demanding answers about whether they were exposed to radiation.
The former sailors say in the last 20 years, more and more of them and their families are getting ill.
The Mururoa veterans gathered in Tauranga over the weekend to mark the 40th anniversary of the mission.
About 500 personnel on board HMNZS Canterbury and Otago were sent to Mururoa by then-Prime Minister Norman Kirk.
The Otago was the first to be stationed off Mururoa and it witnessed one nuclear test. Not long after, the frigate was relieved by the Canterbury, and she was there for a second blast.
While precautions were taken to protect the crew, those on board now believe they may have been exposed to radioactive contamination through sea water taken on board.
Of the 500 crew, the Mururoa Veterans Society says 180 have died and a number are suffering from a number of illnesses, including cancer.
President Peter Mitchell said most of the surviving veterans have a medical story to tell that may or may not be able to be traced back to Mururoa.
Mr Mitchell said while some veterans are entitled to war disablement pensions, Mr Mitchell said they want to find out more about what they were exposed to and whether it's responsible for the the sicknesses that have befallen many of them over the last 40 years.
He said Norman Kirk promised the sailors that went to Mururoa that they would be looked after, but since they returned they have felt neglected and forgotten.